Music score with 'secret writing'

Extract from a music score containing
'secret writing' about the British war effort, 1915.

In July 1915, British censors intercepted four sheets of music being sent
to Norway. It was discovered that they contained 'secret writing' giving
detailed information about various aspects of the British war effort, such
as strikes, conscription and possible military targets for German aircraft.
This extract shows the letter writer, who signed himself 'Cecil', asking
his paymasters for more money so that he could gain information from his
brother about '[Royal] Navy movements'. In October 1915, 'Cecil', whose
real name was Courtenay de Rysbach, was sentenced to life imprisonment for
his espionage activities.
Catalogue reference: KV 1/74 (1915)